More and more pitchers are hearing the word Pronation as it relates to good pitching mechanics. The reason it is becoming more apart of the conventional vocabulary of baseball today is because of the ever rising arm surgeries at all levels of the game.

The reason the rise in arm surgery is causing this terminology to surface is because institutes like the Department of Sport and Exercise Science at The University of Auckland, New Zealand have discovered the importance of this mechanical component to protecting the elbow joint of the arm when throwing as evident in the article called the Evolution of the treatment options of ulnar collateral ligament injuries of the elbow hosted at the British Journal of Sports Medicine. The article describes the issues of the throwing movement on the elbow joint and lists some new discoveries and solutions to these problems. Here is an excerpt from the article stating the importance of pronation to reducing loads on the arm which can lead to injury.

Recent biomechanical analysis has found that coupling of shoulder internal rotation and forearm pronation forms the physiological basis of varus acceleration to minimise valgus elbow load.

Pronation is a critical pitching component because it not only reduces arm injury as stated above but it also supports pitching velocity. It supports pitching velocity by increasing vertical ball movements which is covered in detail below. Now that this information is becoming more conventional and the evidence has proven the importance of pronation as it relates to injury and pitching velocity, the question now becomes do we coach pronation or is it just a result of efficient total body pitching mechanics? Before answering this question here is more evidence covering the important benefits of forearm pronation at pitch release.

Pronation Increases Pitching Velocity

Most pitchers and pitching coaches do not know the importance of vertical ball movement. It is characteristic of most high velocity pitchers especially those who have high strikeouts to “at bat” ratios. This vertical ball movement is the result of optimal pronation speeds at pitch release. The reason high pronation speeds will effect vertical ball movement is because it increases the spin rate of the baseball. This is no different than the effect of spin rate on the spiral of a football. Here is a study performed by the Department of Health Science, Kinesiology, Recreation and Dance at the University of Arkansas, Fayetteville, Arkansas, which proves the relationship of forearm pronation speeds to ball movements. The study is called the Biomechanical analysis of forearm pronation and its relationship to ball movement for the two-seam and four-seam fastball pitches. Here are the results of the case study:

These results suggest that pitchers may be able to manipulate the magnitude of vertical ball movement by altering pronation accelerations at ball release. In addition, it appears that pitchers should alter their current training techniques so as to increase the endurance capabilities of the primary pronator muscles of the forearm. In doing so, they may be able to limit the effects of fatigue on these muscles during pitching, thus preventing a decrease in the magnitude of vertical ball movement that typically occurs late in a pitching performance.

This study does not only claim the importance of pronation speeds to vertical ball movements but it also suggests the training of the pronator muscles in the forearm to prevent fatigue late in a game which would reduce the vertical ball movements as it slows forearm pronation speeds. This case study does not define the reason for the vertical ball movements but only the cause. There is new technology that has explained these vertical ball movements as being the result of high spin rates. This new technology is currently moving into the MLB as they install the new 3D Doppler Radars into MLB parks around the country. The data coming from these radars have proven that high spin rates lead to high strikeout rates. Sports Illustrated documented this data in an article called How a Danish tech company is revolutionizing pitching data by Tom Verducci. He writes:

What also is interesting is that some preliminary data suggests high spin rates also make fastballs harder to hit. Pitchers who don’t throw hard but have high spin rates on their fastball — such as Shaun Marcum of the Brewers and Koji Uehara of the Orioles — post higher strikeout rates than their modest velocity would otherwise suggest.

Here is a data chart from the 3D Doppler Radar showing average velocity to spin rate measured in RPM’s.

Pitcher, Team

Avg Velocity 2011

RPM

Justin Verlander, Tigers

95.0

3,004

Gio Gonzalez, A’s

92.8

2,965

Chad Durbin, Phillies

89.6

2,838

Alfredo Aceves, Yankees

92.1

2,795

Clay Buchholz, Red Sox

92.3

2,740

Tommy Hunter, Rangers

91.9

2,720

Josh Tomlin, Indians

88.0

2,693

Ivan Nova, Yankees

92.4

2,690

Kyle Davies, Royals

91.8

2,669

Brian Matusz, Orioles

88.5

2,637

MLB Average

91.54

2,450

The more popular this 3D Doppler Radar becomes and the more often this data is made public, it should eventually become conventional wisdom to stress the importance of forearm pronation speeds as much as internal rotation speeds of the throwing arm. The traditional velocity readings on the chart here are the results of internal rotation speeds of the arm and the RPM readings are the result of pronation speeds. These speeds along with a pitchers stride distance measure what is called “Effective Velocity,” which is a better and more comprehensive way to asses a pitchers effectiveness than only with ball velocity readings.

Pronation Reduces Pitching Arm Injuries

Here are some more studies claiming the importance of pronation to reducing elbow loads which can eventually lead to injury. Before reading these studies it is important to understand the difference between valgus and varus torque. Valgus is the loads put on the elbow joint when the arm is externally rotated and accelerating . Varus is the loads put on the elbow joint when it is internally rotated and decelerating. If you notice the clip of Tim Lincecum above, you will see that as his arm accelerates forward when externally rotated, his elbow moves into extension. Once the arm fully extends, pronation begins. This extension and pronation is releasing the tension on the elbow because valgus loads are increased with more flexion as stated in the case study by the Department of Orthopedics and Rehabilitation at the University of New Mexico, School of Medicine, Albuquerque called Elbow ligament strain under valgus load: a biomechanical study. Here are the results of the study:

Strain in the anterior bundle was significantly greater than in the posterior bundle and increased with more flexion.

These results indicate that the anterior bundle is important in resisting a valgus load, particularly in mid-flexion, while the importance of the posterior bundle increases as the elbow approaches full flexion.

More proof that elbow tension is released during extension and pronation of the throwing arm is stated in the case study below. This study by the Department of Orthopedics at the Mayo Clinic and Mayo Foundation, Rochester, MN called The effect of forearm rotation on laxity and stability of the elbow states that forearm pronation will reduce valgus and varus loads. In the context of the study this laxity can have a negative effect if the elbow is not in full extension. Here is the results of this study:

The observation that forearm pronation increases valgus/varus laxity, particularly in medial collateral ligament deficient elbows, implies a possible additional factor in throwing kinematics that might put professional baseball pitchers at risk of medial collateral ligament injury due to chronic valgus overload. Our data indicate that forearm rotation should be considered during the clinical examination of elbow instability.

The lesson here is pronation must begin during full elbow extension to reduce the loads on the elbow joint during acceleration. If pronation begins before elbow extension it will make the elbow joint more vulnerable to torque which can cause injury.

Should we Coach Pitchers to Pronate?

Yes, we should coach this critical pitching component as evident in all of these valuable case studies but the key is how do we coach it. The best and only way to coach this component is through total body mechanics. Pronation just like early internal rotation, which is a key component of high velocity pitchers, is the result of optimal hip to shoulder separation. If you can not train a pitcher to convert 3X into optimal hip to shoulder separation, which is the foundation of the 3X Pitching Velocity program, then trying to coach optimal pronation will be a constant up hill battle. The reason optimal hip to shoulder separation leads to optimal pronation is because the throwing arm moves into elbow extension early and above the head. If elbow extension happens late and in front of the face then pronation is limited.

Just watch the clip of Lincecum above. The clips starts with him in optimal hip to shoulder separation as a reaction to his 3X into hip rotation. This separation is allowing him to keep his elbow behind his face during external rotation and also building optimal shoulder and elbow torque. As his arm accelerates forward, he is able to move into elbow extension early to help reduce these loads on his arm while his arm is reaching its peak speed when the loads are the greatest. He is able to continue to move into internal rotation while his elbow is still at ear height. If he did not start with optimal hip to shoulder separation, elbow extension would have happened later in his throwing phase, limiting the amount of pronation which would result in a lower spin rate and increased valgus and varus loads on the elbow. Tim Lincecum’s amazing separation into optimal pronation is the reason he is a high velocity pitcher who has rarely been on the disabled list (DL).

To learn some basic drills to help support the motor coordination around optimal hip to shoulder separation and pronation check out the 3X Pitching Velocity program.

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